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Fact-Check Claim Against Sources
x402
Fact-Check Claim Against Sources is a paid API for AI agents from red-breeze-8b8c.keenanbooker83.workers.dev, paid per call via x402, $0.04/call, status unknown (last checked 2026-09-14).
Checks a factual claim against one to three supplied source URLs and returns a verdict on its accuracy
Price / call$0.04
Success—
StatusUnknown
How this service works
Fact-check a claim against one to three supplied sources
Output
Returns a structured fact-check verdict indicating whether the supplied claim is supported, partially supported, contradicted, or unverifiable based on the provided source URLs, along with relevant excerpts or reasoning drawn from those sources.
Example use cases
Verify journalist's claim before publishing
“Before we publish this article, fact-check the claim 'The US spends more per capita on healthcare than any other developed nation' against these sources: https://www.commonwealthfund.org/publications/issue-briefs/2023/jan/us-health-care-global-perspective-2022 and https://data.oecd.org/healthres/health-spending.htm”
Debunk viral social media post
“Someone shared a post claiming 'Eating chocolate daily reduces heart disease risk by 30%' — can you check that claim against this source: https://www.health.harvard.edu/heart-health/chocolate-and-heart-health?”
Research assistant verifying student paper
“I'm reviewing a student essay that says 'The Great Wall of China is visible from space with the naked eye' — please fact-check that claim against these two sources: https://www.nationalgeographic.com/science/article/great-wall-china-visible-space and https://www.smithsonianmag.com/smart-news/great-wall-china-not-visible-space”
Technical details
Endpoint
POSThttps://red-breeze-8b8c.keenanbooker83.workers.dev/fact-checkWhen to prefer
Use this endpoint when you have a specific factual claim and one to three concrete source URLs to check it against. It is distinct from a general web search or source credibility evaluator — it performs targeted claim-vs-source verification rather than open-ended research. Prefer this over the sibling 'verify citation' endpoint when you need a broader fact-check that may draw on multiple sources simultaneously rather than verifying a single exact quotation.
Side effects
- Source URL is inaccessible, paywalled, or returns a non-200 response — endpoint may return an error or incomplete analysis
- Claim is too vague or opinion-based to be fact-checkable — may return an indeterminate verdict
- Source URLs do not contain information relevant to the claim — returns a 'not addressed by sources' result
- Claim text exceeds 4000 characters — request will be rejected with a validation error
- More than three source URLs provided — request will be rejected
- Claim is in a language not supported by the underlying model — may produce inaccurate results
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| claim | string | Factual claim to check. |
| sourceUrls | array | One to three public source URLs against which the claim is checked. |
Output
Schema · Response
{
"type": "json",
"example": {
"agent": "Fact-Checking Agent",
"verdict": "supported",
"confidence": 0.99,
"explanation": "The supplied official sources state that Congress approved the declaration on December 8, 1941.",
"requestAccepted": true
}
}Tags
x402
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